1. Field of the Invention
The present invention relates to an optical waveguide device connected to an optical cable.
2. Description of Related Art
In recent years, with the increase in speed of data communication, optical communication using optical cables is replacing communication using metallic cables and becoming the main stream. As an optical waveguide device which performs optical communication, there is an optical waveguide device optically connected to an optical cable and the device splits the light transmitted from the optical cable into a plurality of optical cables.
An optical waveguide device comprises an optical waveguide section including a core formed with a plurality of branches in a Y-shape and a clad formed so as to enwrap the core, and a connecting section to fix optical fiber lines and to connect the optical fiber lines to both ends of the core, and the optical waveguide section and the connecting section are both formed on the same substrate.
As for the connection between the optical waveguide device and the optical fiber, it is important that accurate alignment is performed so that loss at a connection point is small and that the connection is fixed so that the connection is not misaligned even when a certain amount of external force is applied.
Thus, a structure in which a V-shaped groove (V-groove) is provided in the connecting section to place an optical fiber line to enable accurate alignment when the optical fiber line is fixed is proposed (for example, see Japanese Patent Application Laid-Open Publication No. 2004-93730, Japanese Patent Application Laid-Open Publication No. 2005-352453).
As shown in FIG. 10A, when a V-groove 114 with a depth of about 100 μm is formed by anisotropic wet etching in a connecting section 113 of a substrate 111, an end face is not flat. Thus, as shown in FIG. 10B, by forming a rectangular groove 115 at a border between an optical waveguide section 112 and the connecting section 113 orthogonal to the V-groove 114 by dicing, and as shown in FIG. 10C, abutting an optical fiber line 140 to a side wall of the rectangular groove 115 on the optical waveguide section 112 side, accurate alignment may be performed (for example, see Japanese Patent Application Laid-Open Publication No. 2002-139641) As a core and a clad of the optical waveguide section 112, polymer material such as polyimide, etc., may be used, and as a substrate 111, a silicon substrate may be used.
As shown in FIG. 10C, the optical fiber line 140 is fixed to the connecting section by placing a glass block 150 on the optical fiber line 140 placed on the connecting section 113 and injecting an adhesive between the connecting section 113 and the glass block 150 while pushing the glass block 150 to the connecting section 113 with a jig (not shown) (for example, see Japanese Patent Application Laid-Open Publication No. 2004-212686).
A gap between the optical fiber line and the core of the optical waveguide section is filled with a transparent UV curable resin with a refractive index equal to that of the core in order to prevent Fresnel reflection loss caused by the air gap.
However, there is a problem that when UV curable resin is supplied more than necessary, the UV curable resin flows into the rectangular groove, and thus when the UV curable resin cures and contracts, the end of the optical fiber line moves causing deterioration of alignment accuracy.